did gm put a nut on top of this bolt with no access anyone had any trouble out of the rear body bolts? mines just spinning , like it's got a nut on top of it.

 

#4 uses a nut plate under a cage, just like #3 & 2, you can access the nut plate in the rer of the cargo area, there are 2 pockets there that allow access to it.

 

so there's access to the top nut in the rear cargo area yeeee haaaaaaaa

 

This is what you see on the outside[IMG][/IMG] This is what you need to look for inside and back in the corners[IMG][/IMG] And this is what you can't see where the nut is turning [IMG][/IMG] Your inside pieces are probably all rusted and need to be replaced. Don't ask how I know.

 

What's happened is the cage around the nut has broken free, the rivets have corroded away and the cage is spinning with the nut. Once you get in there you will have to have two people, one to hold the cage and one to wrench out the bolt. That is a notorius site for rust so I would suggest using a penetrant on it and let it soak. I tore one right through the fiberglass before I knew what was going on so be careful and good luck.

 

On my 1968, the #4 nut catcher was made out of thin steel sheet and was attached to the body with what appeared to be aluminum rivets. This compares with the frame mounted #2 and #3 nut catchers that are of much thicker steel stock and are welded to the frame.

The fact that the #4 nutcatcher is held in with aluminum rivets means that with a little bit of bolt/nut rust, you can easily shear the nutcatcher rivets and then have a very difficult time getting the nut out. On the Convertible, access to the nut is blocked by the spring/hindge mechanism of the softtop storage panel door.

 

The cage might not have broken loose. I have had problems of the nut spinning and pressing the thin walls outward. Simple fix for that problem though. Use some vice grips and pinch the cage closed and grab onto the nut.

 

With 20/20 hindsight this is is the way I should have started to attack my problem. (But, actually it wouldn't have helped me out with what was my real problem.) When I initially realized I had a spinning #4 nut, I realized I'd have to take off the convertible hinge mechanism to get at it. To make a long story short...that looked difficult and I was impatient to get on the the job of getting that bolt out. I decided to drill a hole in the fiberglass body that was in line with the spinning nut. I then inserted a machinist's punch into the hole to jamb the nut and prevent it from spinning while I unscrewed the bolt head. I thought this was a good idea. It didn't work, although I think it should have .....(an hour passes, air powered impact wrench is brought into the fray)... I ultimately found out that the problem was that the bolt was not that it was rusted to the nut...it was cross threaded!!! There was no way that this bolt would ever be unscrewed. When the car was made, someone on the assembly line used an air powered tool to torque what was really a crossthreaded bolt/nut. 37 years later with a little rust, there was no way this bolt/nut was going to unscrew. .......I'm a little embarrassed to say how I got the bolt out, because I ended up doing damage to the body. I've bought a new #4 body steel part (kinda looks like a U cup) from Volunteer Covette (I pretty much destroyed the original.) Volunteer seems to have a lot of these body parts. If I decide to proceed on with lifting my body, I will do a proper repair of this mount.

 

I had the same problem with my #4 mounts. I found it easier to just cut the bolt shank from underneath.












www.bigdogvettes.com

 

Most likely that the aluminum rivet coroded away. Use vise grips from inside car to hold the square nut and another person under car, after using a rust buster.

 

Mine is a '79 and I don't have the cage around the "nut". If you don't have to replace the cage (rust) don't take it out - just cut the bolt head off.
I replaced the bolt and re-installed the new one with the head inside the car, put a huge fender washer under the head...the nut is now outside the car.
I'm not sure about '77 and older models, on my '79 I can hold the bolt head with a wrench (inside the car)....

 

I had to cut the entire thing outta the car, as the steel cups wit the rivits through them were rusted out totally, so it all came out, and new stuff went in all bedded in epoxy with stainless bolts/nuts all around....

GENE

 

Save yourself time and aggravation....Cut the bolt from the outside.
Eddie

 

YUP - 4 1/2" grinder ... take the head of the bolt off.
Also, consider the fact that you may need to remove or replace the
steel body reinforcement. In the end, most people take the cage
assembly out and simply replace with a bolt inserted from the top
with a big washer.

Here is my thread on working this area. In hindsight, I would use
1/4-20 stainless bolts to attach the reinforcement.
http://forums.corvetteforum.com/showthread.php?t=872065

 

thanks for the info guys , i should of mentioned that my car was a vert , looks like i'll have to remove the spring mech for the rear deck lid to even get back in the area.

 

On the passinger side I shreaded the fiberglass around the hole because the nutplate spun, the rivets and nutplates where rusted beyond repair, On the drivers side I drilled out the aluminum rivets attaching the nutplate to the pocket and removed the nutplate before removing the bolt/nut so I wouldn't damage the fiberglass. I have made square aluminum .140" thick retainer plates with the nutplates and nuts attached to nest into the pocket area, I will add fiberglass to the damaged side prior to installing the plate, This should bond my plates into place.

 

Yep...I did...and used stainless lock nuts inside. Can't rivet that reinforcment with body on anyway!!
Eddie

 

I used 1/4" aircraft titanium type hilocks to attach the reinforcement to the body. It's nice to have access to aircraft fasteners.